The invention applies to the field of furniture.
So-called coplanar door units are well known and widely used for closing openings on furniture or as doors used in various living environments. Coplanar doors, when in a closing position, generally have their main surfaces lying on a same vertical plane and opening of a passageway closed by the doors is carried out by pushing back one of the doors and therefore sliding it behind a second door which remains stationary, or vice versa by drawing or pulling one of the doors and sliding it over the other door which remains temporarily stationary. Movement may be applied to either of the coplanar doors. For aesthetic and practical reasons it is desired that each door is kept parallel to itself in its closing position, in its intermediate retracted or extracted position, and in its opening position n when it overlaps a second door.
A coplanar door movement mechanism of four-bar linkage type is already known. This mechanism includes a carriage movable for a horizontal traverse parallel to the door plane, and two parallel connecting rods or links assembled on the carriage and supporting a door. To open the door, the user pushes it from its steady closed position to its retracted (respectively extracted) intermediate position, then slides it behind or before, respectively, a second door held stationary. Since, during a first movement step, the carriage stays still, the first door, passing from its steady closed position to its retracted or respectively extracted position, moves along a circular are round the connecting rod fulcrums on the carriage. Such are motion, although of limited extent, is undesirable since it means that a relatively wide clearance is needed between a door""s vertical edge and a fixed structure facing it, and because it means that a door must be bevelled so as not to interfere with an adjacent door.
An aim of the invention is to achieve an opening/closing coplanar door movement that produces a straight shifting of the door between its closing position and its intermediate retracted or extracted position and vice versa, i.e. in which each vertical door edge substantially moves in a plane.
An additional aim is to realize such a device that keeps the door parallel to itself in every position.
An additional aim of the invention is to realize a device of limited bulk, that may be hidden from view by the furnishing portions whereon it is assembled and that is easy to assemble as a single item.
Such aims have been reached with a mechanism as said in claim 1 and an assembly as said in claim 10. Additional new and useful characteristics are said in the following claims.
The mechanism of the invention includes a pair of levers or connecting rods arranged as a four-bar linkage, each assembled by a pivot on a sliding carriage, and a compensator unit to make the carriage slide, each time the connecting rods are rotated to retract or extract the door, carried on them, by an extent that is equal and opposite to the extent of the projection, on a carriage track, of an arc travelled by the door. The compensator unit is generally of cam type. More particularly, the compensator unit includes at least a slider which is moved by a tab extending from a connecting rod of the four-bar linkage, each connecting rod forming a first class lever. The slider is longitudinally movable along the carriages for a length and at one end thereof has a movement control lever engaging a cam recess in a mechanism stationary structure with a cam roller. A spring between the slider and the carriages biases the mechanism to its stable condition with the connecting rods or links in a condition in which the door is in the closing position. The mechanism can be enclosed in a thin casing that internally forms a cam part and the sliding track for the carriages.
Each door is preferably assembled on a said mechanism at its upper edge and on another said mechanism at its lower edge, the carriage unit of the mechanism preferably occupying a lengthwise extension of no more than half the door width. Preferably the upper and lower mechanismns are interconnected with at least one bar which is rigidly secured to a connecting rod of the upper mechanism and a corresponding connecting rod of the lower mechanism to ensure a consistent shifting of both mechanisms and a door movement wherein the door is always parallel according to vertical planes.
The new device achieves the above mentioned aims, particularly allows each door of a set of coplanar doors to move parallel to itself along perpendicular axes. Moreover, it is of compact construction. It could be entirely factory built, with only simple mounting operations required for assembly to a door and the item of furniture or the structure of which the door is part.